balance the oxidation reduction PbO2 yields Pb2+ + O2

Answer :-

oxidation number of oxygen in compound state is -2 

so the oxidation number of Pb in PbO2 

Pb + 2(-2)  = 0 

             Pb = 4 

and Pb +2 has oxidation number +2 

              change in oxidation number is 2-4 = - 2  (reduction )

oxidation number of oxygen in O2 is 0 

so change in oxidation of oxygen is  0- (2)  = 2 (oxidation )

and there are oxygen atom there

                so change in oxidation number is = 2* 2 

                                                                      = 4 

 there ratio of oxidation and reduction is  4  :  2   = 2  :   1  

cross multiply by these relation we get